Device for the automated monitoring of packaging machines for the production of sausages

ABSTRACT

The subject matter of the invention is a device and a method for the automated monitoring of packaging machines for the production of sausages, the packaging machines having a filling machine (F), a filling pipe ( 1 ), a skin brake ( 2 ) and a sealing machine (V). The device according to the invention is characterized in that it has a camera ( 6, 6′, 6″ ) which supplies an electric image signal, an evaluation unit ( 7 ) for the image signal and a switching-off unit ( 8 ), which is activated by the evaluation unit, for the filling machine (F). The invention permits automated monitoring of malfunctions of packaging machines for the production of sausages.

The invention relates to a device for the monitoring of automatedpackaging machines for the production of sausages. These machines serveto fill sausage meat into an artificial or natural skin and to seal therespective ends of the skin.

Packaging machines for the production of sausages within the meaning ofthe invention comprise the following components:

-   -   a filling machine which presses the sausage meat into the input        end of a filling pipe,    -   a skin brake which is arranged at the output end of the filling        pipe, and    -   a sealing machine for sealing the skin.

The packaging with the aid of machines of this type usually takes placeas follows:

-   -   First of all, an empty skin which is closed on one side and has        a large length is pulled onto the filling pipe from the output        end thereof. It is then generally gathered to form a bead.    -   The skin brake is then brought into its working. position. The        skin brake is a device which puts up a frictional force to the        removal of the skin from the filling pipe. Without a frictional        force of this type, the skin would be only nonuniformly removed        from the filling pipe, for which reason uniform packaging would        be scarcely possible. The skin brake generally comprises one or        more rings made of elastic material which surround the filling        pipe. When a skin is situated on the filling pipe, the latter is        pressed by the elastic material onto the surface of the filling        pipe, thus producing the desired frictional force when removing        it. The working position of the skin brake is a location at the        output end of the filling pipe (cf. DE 199 53 695).    -   The filling machine is set into operation. The meat passes        through the filling pipe into the skin. Since the latter is        sealed at the output end, it is gradually removed from the        filling pipe. The skin brake just described ensures that this        takes place uniformly.    -   The skin filled in this manner is supplied to the sealing        machine which seals it section by section.

This can take place, for example, by the machine constricting the skinwith displacers and then placing clips onto the constricted region, theclips becoming deformed when pressed onto a die and thereby forming aseal.

The invention relates especially to automated packaging machines for theproduction of sausages. These packaging machines operate continuously,i.e. the working steps are coordinated with one another in such a mannerthat individual sausages are continuously packaged to form a chain ofsausages or to form individual, divided sausages.

In machines of this type, the problem regularly occurs that the momentwhen the skin ends has to be detected, so that the filling machine canbe switched off in good time. Similarly, the filling machine has to beswitched off immediately if there are what are referred to as“bursters”, i.e. if the filled skin which is removed from the fillingpipe unintentionally bursts. It is uneconomical to have a personcontinuously monitoring the machine.

There are therefore numerous proposals in the prior art for theautomated monitoring of the packaging. It has therefore been proposed,for example, to fasten a crocodile clip to the end of the packagingtube, said crocodile clip flipping a switch when the end of the tube hasbeen set in motion. A drag lever has also been thought of, on which thegathered skin rests and comes into contact with the metallic fillingpipe as soon as the tube is removed. By producing the contact, anelectric switching circuit is closed and produces a correspondingsignal. However, with these innovations, only the reaching of the end ofthe tube could be detected but not, by contrast, malfunctions, such as aburst tube. However, this is made possible by a running wheel in the endregion of the filling pipe, which running wheel rests on the tubematerial and is driven by the latter if the latter is removed correctly;if the wheel is at a standstill, which is detected by a sensor, there iseither an error or the end of the tube has been reached (cf. EP 0 755188 B1).

The previously known solutions therefore either do not detect anymalfunctions or they make use of mechanical and mechanical componentswhich involve a considerable outlay on maintenance.

The invention has the object of permitting a monitoring both ofmalfunctions and of the reaching of the end of the tube, the monitoringmanaging without mechanical components.

The invention achieves this object by means of the features of thecharacterizing part of patent claim 1.

In this case, a camera is any desired optical recording system for atwo-dimensional image supplied by the system as an electric imagesignal. In this case, the term “electric” also covers the term“electronic”.

An evaluation unit is a computing unit which can store images and cancarry out comparison operations on them.

A switching-off unit is an electronic unit which switches off thefilling machine in response to a signal from the evaluation unit.

The evaluation unit and/or the switching-off unit may either beintegrated in the camera, filling machine or the like or else may bedesigned as one or two separate components.

The device functions, for example, with the following method which is tobe carried out by the evaluation unit:

A method for the automated monitoring of packaging machines for theproduction of sausages, the packaging machines having

-   -   a filling machine,    -   a filling pipe,    -   a skin brake, and    -   a sealing machine,        characterized by the following steps:        -   a) An initialization value is written to an initialization            memory.        -   b) A region of the packaging machine is photographed with a            camera.        -   c) The image recorded by the camera is digitized.        -   d) The digitized image is stored in an image memory.        -   e) If the initialization memory contains the initialization            value, the latter is overwritten with another value and a            new operating cycle beginning with step b) is started.        -   e′) Otherwise, the image stored according to step d) is            compared with an image stored previously in the operating            cycle according to step d).        -   f) If the comparison according to step e′) reveals a            difference between the images, the image memory occupied            previously in the operating cycle according to step d) is            released and a new operating cycle begins at step b).        -   f′) Otherwise, a switching-off unit is activated, so that            the filling machine is switched off.

In addition to or instead of the switching off of the filling machineaccording to step f′), a warning signal can be output and/or otherfunctions, for example a switching off of the sealing machine, can betriggered.

A different region of the packaging machine to the one photographed bythe camera according to step b) may be selected.

It is conceivable to photograph a region of the bead formed by the skin,on the filling pipe (“bead region”). The region then has to be selectedin such a manner that the skin in it is constantly in motion if theremoval process is functioning correctly. However, in the case of aburster, the following meat no longer exerts any pressure which couldremove the skin. The skin therefore no longer moves, with the resultthat, in the case of the comparison according to step e′), no differencebetween the images is established and the cycle diverges to step f′)and, consequently, the filling machine is switched off. If the end ofthe skin is reached, the skin disappears from the image region selectedin this setting. The images following one another are identical, so thatthe cycle again diverges from e′) to f′). Within the context of theinitialization, separate steps can also be provided to photograph theblank filling pipe without the skin and to store this image as an emptyimage. In addition, before the switching-off unit is activated accordingto step f′), a comparison of the empty image with the image taken lastcan be carried out. If this comparison does not supply a difference,then there is no burster but rather the end of the skin is reached. Thismakes it possible to differentiate between a burster and the reaching ofthe end of the skin, and this can be taken into consideration in thetriggering of the further functions.

It is also conceivable to photograph a region with a section of the skinbetween filling pipe and sealing machine (“balloon region”). If themachine operates correctly, then the skin inflates in this region atperiodic intervals to form balloons of constant size. If two imagestaken consecutively are identical, there is an error, with the resultthat the cycle diverges from e′) to f′). However, the abovementionedmethod can also be changed in step f) to the effect that, if there is adifference, the cycle diverges to step f′) and, if consecutive imagesare identical, it jumps back to b). In addition, the photograph in stepb) has to be coupled to the cycle of the machine, i.e. the photograph isalways taken if the machine is in a certain phase, for example if theballoon is particularly inflated. This also makes it possible toestablish fluctuations in the size. Fluctuations of this type are oftenan indication of deficient quality of the sausages produced, for examplebecause the meat does not have the correct temperature, or the like. Inthis method, it is not absolutely necessary for consecutive images to becompared. It is also conceivable that, in addition or instead of this,the image photographed last is compared in each case with a desiredimage. The desired image can be photographed within the context of theinitialization process or can be predetermined in some other manner andin each case stored.

Finally, it is also conceivable to direct the camera at the outletregion of the sealing machine where the finished sausages drop out orroll out at periodic intervals (“sausage region”). If no sausage appearshere, there is an error, or the end of the skin has been reached. As isthe case with photographs in the balloon region, it is also conceivablehere to synchronize the photographs according to step b) with themachine cycle in order also to monitor the quality of the sausages. Thisis because, in the event of fluctuations in the quality, the size and/orthe shape of the sausages also change. It is conceivable to measure thearea of the sausage included in the image. This can take place, forexample, by the photographing in color, the color of the skin beingstored in the evaluation unit and this unit then determining the numberof pixels which have this color and are linked together in an area. Thenumber of pixels is then a measurement for the area. In a correspondingmanner, the length (by determining the longest straight line in thearea) or other shape properties can be determined and monitored. Thecolor of the skin can be determined either in an initialization step orelse continuously by a region of the skin in the region of the bead orballoon additionally being photographed. In these method variants, colortolerances can be taken into consideration and, if appropriate, lightfluctuations having an effect on the color of the pixels can thus bedetermined.

Instead of only photographing one of the abovementioned regions, thebead, balloon and sausage regions can also be photographed incombination with one another. For this purpose, a plurality of camerascan be used. It is also conceivable to photograph two or more regionswith one camera and to allow the evaluation unit only to evaluate theappropriate image excerpts. In this case, in particular theabove-described, simple methods and the cyclic methods could also becombined with one another, so that the monitoring overall becomes morereliable.

The evaluation does not have to be restricted to the comparison ofstatic images. Films can also be taken (actual films) which arecontinuously compared with a representative film which has either beentaken during the initialization process or in an operation runningcorrectly (desired film). It is also conceivable either to incorporateone, two or else all three regions from the bead, balloon and sausageregions into the evaluation and to operate with one or more cameras. Itis likewise possible to couple the beginning of filming with the machinecycle.

Finally, it is also possible to combine film and static image evaluationwith one another. Thus, it is, for example, conceivable to select thebead region in order to monitor bursters and the reaching of the end ofthe skin and to select one or both of the other regions in order tomonitor the quality.

The transportable display unit for visualizing the image taken with thecamera and having a receiving unit, and a transmission unit fortransmitting the image signal to the receiving unit are advantageouslyadditionally provided. These units can serve, when a signal istriggered, to display to the operator who is carrying the display unitwith the receiving unit with him the image last photographed or the filmlast taken.

Two exemplary embodiments of the invention are explained in greaterdetail below with reference to the drawings, in which:

FIG. 1 shows a diagrammatic illustration of a packaging machine for theproduction of sausages with three cameras and in each case separateimage regions;

FIG. 2 shows the same illustration with just one camera with acomprehensive image range.

A packaging machine comprises a filling machine F to which the one endof a filling pipe 1 is fastened. A skin brake 2 sits on the other end ofthe filling pipe 1. The end of a sausage skin, which is illustrated herediagrammatically as a bead 3, is situated on the section of the fillingpipe 1 upstream of the skin brake. On the other side of the skin brake2, a sealing machine V follows the filling pipe 1. The outlet region ofsaid sealing machine is situated on its opposite side where a sausage 5dropping out is shown. The skin forms a balloon 4 between the pipe 1 andthe sealing machine V.

A respective bead region R, a balloon region B and a sausage region Ware shown in each case by dashed lines. A camera 6, 6′ or 6″ is directedat each of the regions. As can be seen in FIG. 2, the three cameras canalso be replaced by a single camera 6 which photographs a larger regioncovering the regions R, B and W.

As further illustrated in FIG. 2, an evaluation unit 7 is connected tothe camera 6. A switching-off unit is formed from a cable 8 andinterfaces (not illustrated) in the evaluation unit 7 and the fillingmachine F. Moreover, the evaluation unit 7 is connected via a cable to atransmission unit 9 which can transmit by radio the image photographedlast or the images photographed last to the receiving unit of atransportable display unit 10.

1. A device for the automated monitoring of packaging machines for theproduction of sausages, the packaging machines having a filling machine(F), a filling pipe (1), a skin brake (2) and a sealing machine (V),characterized by a camera (6, 6′, 6″) which supplies an electric imagesignal, an evaluation unit (7) for the image signal and a switching-offunit (8), which is activated by the evaluation unit, for the fillingmachine (F).
 2. The device as claimed in patent claim 1, characterizedin that a transportable display device (10) for visualizing the imagetaken with the camera (6, 6′, 6″) and having a receiving unit, and atransmission unit (9) for transmitting the image signal to the receivingunit are additionally provided.
 3. A method for the automated monitoringof packaging machines for the production of sausages, the packagingmachines having a filling machine (F), a filling pipe (1), a skin brake(2), and a sealing machine (V) , characterized by the following steps:a) an initialization value is written to an initialization memory; b) aregion of the packaging machine is photographed with a camera (6, 6′,6″); c) the image recorded by the camera (6, 6′, 6″) is digitized; d)the digitized image is stored in an image memory; and e) if theinitialization memory contains the initialization value, the latter isoverwritten with another value and a new operating cycle beginning withstep b) is started; e′) otherwise, the image stored according to step d)is compared with an image stored previously in the operating cycleaccording to step d); f) if the comparison according to step e′) revealsa difference between the images, the image memory occupied previously inthe operating cycle according to step d) is released and a new operatingcycle begins at step b) f′) otherwise, a switching-off unit isactivated, so that the filling machine (F) is switched off.
 4. Themethod as claimed in claim 3, characterized in that, in addition to orinstead of the switching off of the filling machine (F) according tostep f′), a warning signal is output and/or other functions, for exampleswitching off the sealing machine (V), are triggered.